1. Field of the Invention
The present invention relates to a capping device suitable for a recording apparatus provided with an ink jet recording head movable in the width direction of a recording paper and for ejecting ink drops onto the recording paper in accordance with printing data so as to form an image thereon.
2. Description of the Prior Art
An ink jet recording apparatus ejects ink pressurized in a pressure generating chamber onto a recording paper from a nozzle as ink drops so as to record printing data. This type of recording apparatus has the following problems, that is, increase of viscosity of the ink and solidification of the ink caused by the evaporation of a solvent from the opening of the nozzle, adhesion of dusts, mixing of bubbles in the ink and so on.
Therefore, such an ink jet recording apparatus usually has a capping means for sealing nozzle openings of a recording head at the time of not printing, and a cleaning means for cleaning a nozzle plate in accordance with necessity.
For example, in Japanese Patent Publication No. Hei. 1-125239, there is provided a sled to be pushed out and moved by a carriage which has moved to its home position. The sled moves to a nozzle opening face of a recording head along an inclined guide face provided in a frame, and a rubber cap provided in the surface of the sled is pressed onto the recording head so as to seal nozzle openings.
In addition, in Japanese Patent Publication No. Hei. 2-13910, two arms constituting a parallelogram link is interposed between a frame and a cap as means for pressing the cap against a recording head so as to move the cap by means of a carriage not only horizontally but also toward the recording head.
In these capping means, the quantity of vertical movement is determined by the inclined guide face on the frame or parallelogram link. Accordingly, in the case where more or less scattering arises in the distance between the running course of the carriage and the frame due to an error on finishing or assembling parts, or in the case where the distance between a platen and the recording head is readjusted for printing on thick printing paper such as envelope, the distance between the recording head and the cap is changed and therefore the sealing effect of the nozzle openings depends on the elastic deformation of the cap itself. This especially causes no particular effect if the sealing face is small, but a gap is apt to arise in the case of sealing an ink jet recording head such as a color printing recording head, which is large enough to have a number of arrays of nozzle openings, so that reliable sealing cannot be expected.
In addition, as disclosed in Japanese Patent Publication No. Sho. 59-103762, an inverted-L head protective cover is pivoted at a point on a home position, and the protective cover is rotated by a carriage moved back to the home position, so as to press a cap provided at one end of the protective cover against an ink jet recording head.
According to this capping device, the rotation quantity of the protective cover changes in accordance with the distance to the nozzle face, so that it is possible to seal the recording head positively even in a recording apparatus where the distance between a platen and a printing head changes, but the moving direction of the recording head is different from the moving direction of the cap, so that there is such a problem that relative movement between the both causes unnecessary deformation in the cap so that the cap is apt to be fatigued or damaged.
In order to solve such a problem, as disclosed in Japanese Patent Publication No. Hei. 6-8460, there is provided a capping device comprising a cap disposed outside a printing region and pressed by a recording head or a carriage holding the recording head so as to move between a non-capping position and a capping position, and a cum surface and a cum follower for moving the cap toward a nozzle plate of the recording head when the recording head moves from the non-capping position to the capping position. According to this configuration, it is surely possible to contact the cap with the nozzle plate elastically and seal the cap only by moving the carriage positively.
However, a color-printing ink jet recording head where the arrays of the nozzle openings for ejecting ink of three colors are integrated in a single nozzle plate has been put into practical use, and the length in the printing direction of a recording head has been expanded about 6 times as large as that of a recording head for ejecting a single-color ink. As a result, there has arisen a problem of reduction in the sealing performance, and so on.